The present invention relates to a new and improved apparatus for eliminating metallic contaminations from a fibre transporting duct in spinning preparation, within which duct fibre flocks are transported by an air stream.
Fibre bales very often contain metallic objects which are pressed into such bales in the form of contaminations which are undesirable during spinning preparation. In modern spinning plants where bale opening is effected mechanically and fibre transport to the individual opening and cleaning machines is effected pneumatically within fibre transporting ducts, the detection and elimination of such metallic objects proves extremely difficult. Furthermore, waste fibres, which are re-processed, also often contain metallic contaminations. Additionally, metallic objects can enter the fibre transporting stream due to personnel negligence.
The mentioned metallic objects or the like present a great danger for the plant inasmuch as they can generate sparks and thus can cause fires. Also they can damage the transporting fans or the subsequently arranged processing machines. Therefore, attempts have been made to eliminate metallic objects from the fibre transporting ducts.
According to a device which has become known in practise two magnetic plates are arranged in a bend of the duct. These magnetic plates are offset with respect to one another in such a manner that metallic objects not caught by the first plate impact the second plate and adhere thereto. The magnetic plates can be pivotably opened for eliminating the metallic objects. This prior art device, however, presents serious disadvantages. Thus, only magnetic metal objects are held back while all other metallic objects such as, for instance, aluminum, are not eliminated. Furthermore, it can happen that magnetic metal objects can be transported between the plates without being caught.